Electrically operated gear shift and clutch control mechanism for transmissions



March 1954 c. A. NERACHER 2,671,351

ELECTRICALLY OPERATED GEAR SHIFT AND CLUTCH CONTROL MECHANISM FOR TRANSMISSIONS 6 She ts-Sheet 1 Filed Dec. 19, 1949 til viilw $71M 4. jAJ JQ/ $442 44 March 9, 1954 C. A. NERACH ELECTRICALLY OPERATED CONTROL MECHANISM FOR TRANSMISSIONS Filed Dec. 19, 1949 GEAR SHIFT AND CLUTCH 6 Sheets- Sheet 2 all 07/ 225 March 9, 1954 v c. A. NERACHER ELECTRICALLY OPERATED GEAR SHIFT AND CLUTCH CONTROL MECHANISM FOR TRANSMISSIONS 6 Sheets-Sheet 3 Filed Dec. 19, 1949 [al/Q 93% gm um \Q Q f h QN\ March 1954 c. A. NERACHER ,67 ,351

ELECTRICALLY OPERATED GEAR SHIFT AND CLUTCH CONTROL MECHANISM FOR TRANSMISSIONS 6 Sheets-Sheet 4 Filed Dec. 19, 1949 \WNW March 1954 c. A. NERACHER ELECTRICALLY OPERA TED GEAR SHIFT AND CLUTCH CONTROL MECHANISM FOR TRANSMISSIONS 6 Sheets-Sheet 5 Filed Dec. 19, 1949 mm, ohN

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6 Sheets-Sheet 6 2,671,351 AND CLUTCH SSIONS OPERATED GEAR SHIFT ISM FOR TRANSMI C. A. NERACHER ELECTRICALLY CONTROL MECHAN March 9, 1954 Filed Dec. 19, 1949 Patented Mar. 9, 1954 UNITED PA 5 F91 CE --57- Claims.

The present inventionifrelateszto EGHIEJShlfting mechanism and more particularly ito an automatic control mechanismwhereby. azchangespeed gear device'as; for exzimplegetniautomotive transmission 'mayabe shifted? betweenztivocdifierentconditions representingzdifierent speed ratios, the mechanism operating; under thezinfluence'of vehicle driving conditions, pri-i-icipallyssas they aiiect the speed of the transmission .driven shaft and consequently :of :the vehicle-to effect either 1 an up-shift or a downeshiftgasz the case :maybe.

.Still more specifically, :the invention :relates toia' control mechanism of this type wherein the actual shift "of the change-speed :gear device :is

effected by the positive application tothesh-ifting' element, persse, (Mhichnnayabe:the-shift: fork of a more .or. less conventional 'transmissiomi-of a power-initiated ;force :or athrust in which :the source ofpower isiderivectfrom an electricimotor which, in lturn, derives its energizing :current from theusual battery :employed in attic -=vehicle for ignition and othenpurposes.

The :control'mechanism per iseiis in: the: main, of; an electrical nature; and :whilei-it-is, 78S. stated above, responsive to the-speed of: rotation: of the output or driven shaft of .theetransmission' for effecting either :an up-shiftxpr aflowmshif-t, it is also responsive ;to voluntary acts of :control on the part of thendriver'. ofntheivehicle torefiect such shifts when theyvaredeemedvto be-required bythe driver.

While the present invention is "capable :of use in connection with a large avariety ofi'transmissions having a shiftable element! for effecting the desired changes in I gear ratio, it iSmaflSO rapplicable to existing transmissions which, by a-:.conversion'process, may be adapted for such-tautomaticshifting as outlined above.

In either case, the invention-nas ier its general object the provision of --an -automotive transmission which relieves :thetdriver of'the --vehicle of much of the clutclrpedatandgean shiftnperations thatiare ordinarily :associated withstandard transmissions.

Briefly, the invention involves in its generaliorganization a cyclicly operable mechanism including a clutchthrow-'oiit cam aniiea 'gear -shift cam, the two cams being mounted for rhtation in unison on a cam sha'ft. 'The clutch throwout cam is operatively connectedby a -suitabie linkage tot-he "clutchme'chanism of "the vhicle for clutch throw-outa'nd "clutch jre entr-y' operations. The gear shift -ca'm -'-is-*likewise-operatively connected by a suitable lin agefto the mov- *abie --'gear "shift *eiem'ent "6f *tne nansmissitn "for :efiecting up shiftand down-shift operationss.-as desired.

' The cam shaft upon which the twoscamssare disposed is mounted for alternate rotation'in'fopposite directions r throughout .one complete EI'GVO- lution= during each cycle -to'- effect: an -up-shiftinf 1-thetransmissiongearing in one case and a: downshift. thereof the other.

:A reversible electriczmoton is operatively geared to the. camshaft and areversible.switclrassembly is: provided for reversing the direction ;of zvfiow of current through the field windings of theimotor to thereby determine the direction of'rotationnf the motor. The reversing switch operates-under the control ofa third or reversing switoh cam, through suitable relay control mechanism r-to eifect opening of the motor circuit at the endaof each shift cycle or complete revolution of :the

cam shaft in-either direction to'stop -themotor,

and also to prepare the motor circuit-"forwsubsequent- .energization :andconsequent operation of the motor in the opposite-direction when the next-shift cycle is: in order.

During each shift cycle, regardless :of whether an up shift or a down-shift of .the transmission -is to"be, -performed, :a complete revolution of the clutch throw-out .and re-entry-. cam and of 'the gear-shift cam causes these two camssto=oper ate and {perform their respective; functions :in timed relationship to each other t0;.prod-uce-a ygear shifting operation which substantially-duplicates the functions; manually performed cby t the 'driverofa vehicle as-regards clutch throw-out, gear shifting and subsequent'clutch. re-entrytoperations making use of the tusual :clutch :Lpedal andgear shift lever ofa standard transmission.

Among-the electrical controls involvedin cfonnection *tvith the 4 present *invention *is a selector switch which may-beconditioned for: either'manual orautomatic operation ofthe "vehicletransmission. The usual manual shift lever pr the transmission is left intact "and during automatic operation of the transmission, this'le'vr '"will'be observedto move-automatically accorliingtoLach .gear shift operation 'so that the -driver..inaylbe appraisedof the particulangearratio under which the vehicle-isoperating. -A-;governor associated with the .output or drivenshaft of :the transmis- =sionfidetermines ithe speed at-which the auto- -matic gear; shifting operations shall litake :place.

The governor also operates :to prevent downshifting operations "which ordinarily woii lii take place upon a rim depressi'on of the-accelerator pedal when the vehicle is moving at speedswr'hich The electrical controls also include a so-called automatic kickdown in the form of a suitable switch mechanism which goes into effect upon depression of the accelerator pedal beyond its wide open throttle position. This automatic kickdown arrangement permits a down-shift of the transmission, with consequent immediate acceleration of the vehicle, when the vehicle is traveling at a rate which is higher than the predetermined speed at which the governor is set. Since this throttle kickdown is useful only at'relatively low speeds, means are provided. for

rendering the electrical controls ineffective to obtain the kickdown above predetermined high vehicle speeds. 7 One of the important features of the inven' tion resides in a means whereby during that portion of each shift cycle or complete revolution of the cam shaft during which the actual gear shift takes place, the speed of rotation of the reversible electric control motor may be reduced without aifecting its torque application. In this manner, full motor power and speed are available for rapid clutch disengagement, but the motor speed is reduced during the actual gear shifting operation so that a slow and positive gear shift is effected. Full motor speed is restored during the clutch re-engagement portion of the gear shift cycle. The specific means employed for reducing the motor speed consists of 9. vibrating magnetic relay device which interrupts the flow of armature current to the motor intermittently. Such intermittent application of force to the movable gear shifting unit of the transmission effects an extremely smooth yet powerful gear shift operation and involves less wear and tear on any synchronizing devices which may be employed in connection with the transmission. In other words, because the synchronizing force is intermittently relieved. the clutch teeth which are to be synchronized are constantly moving to slightly different positions relative to each other. Such intermittent application of force to the movable gear shifting unit of the transmission also prevents deadending of the meshable clutch teeth.

The electrical controls associated with the present invention also include a neutral switch which operates to prevent the electrical control system from going into effect to attempt a gear shifting operation when the transmission is in its neutral condition, in reverse, or in any other gear ratio from which automatic shifting is not contemplated.

Numerous other driving and operation contingencies are accommodated by the present invention and these will be described subsequently. For example, the invention contemplates the provision of a control knob for engaging the clutch of the vehicle when the engine is not running, in order that the vehicle may be pushed to start the engine or that the engine may be used as a brake when parking. Additional means are provided for preventing an up-shift of the vehicle during the application of braking torque thereto.

Still other features of the present invention which will be described subsequently are a means to provide manual emergency clutch re-engagement in the event that failure of the electrical system occurs when the clutch is disengaged, and a throttle dashpot device which is inserted in the carburetor throttle linkage so that the speed of throttle closure is rearded as it approaches closed throttle position to prevent the engine from decelerating too rapidly during the interval that the clutch is disengaged and so that the engine will not act initially as a brake on the vehicle and cause an objectionable negative lurch at the commencement of a shift cycle.

Yet another object of the invention is the provision of a means for grounding the primary coil of the ignition system of the vehicle or otherwise rendering the system inoperative to produce an electrical discharge or spark at the terminals of the engine spark plugs during that portion of the gear shift cycle when the clutch is disengaged and the transmission passes through its neutral condition. By such an arrangement the engine is prevented from racing 7 if the throttle happens to be fairly wide open during a transmission down-shift. Additionally, forward lurching of the vehicle is prevented at the time clutch re-entry operations take place during the shift cycle.

The provision of an electrical control arrangement of the type briefly outlined above being the principal object of the invention, other objects and advantages thereof will become more apparent as the nature of the invention is better understood.

In the accompanying six sheets of drawings which form a part of this specification:

Fig. l is a schematic View showing a transmission operatively associated with a clutch mechanism and also showing the manner in which the transmission and clutch mechanism are associated with the control mechanism comprising the present invention; in this view, the shifting forks and countershaft are shown displaced and respectively from their true positions in the vehicle transmission;

Fig. 2 is a top plan view of the assembled transmission housing and clutch bell housing and showing the control mechanism of the present invention applied thereto;

Fig. 3 is a sectional view taken substantially along the line 3--3 of Fig. 2 in the direction indicated by the arrows;

Fig. 4 is a sectional view taken substantially along the line 4-4 of Fig. 2 in the direction indicated by the arrows;

Fig. 5 is a sectional view taken substantially along the line 55 of Fig. 3 in the direction indicated by the arrows;

Fig. 6 is a fragmentary sectional view taken substantially along the line 6-5 of Fig. 3 in the direction indicated by the arrows;

Fig. 7 is an electrical circuit diagram for the electrical control instrumentalities of the present invention;

Fig. 8 is a time chart of the electrical control devices employed in connection with the present invention; and

Fig. 9 is a sectional view taken substantially centrally through a relay magnet employed in connection with the present invention.

In all of the above-described views, like characters of reference are employed to designate like parts throughout.

Referringnowto the drawings in-detail and in particular to- Figs. 1 and 2, a transmission capable of being operated by the cyclicly operable control mechanism of the present invention isschematically shown in Fig. 1 at I8 and is provided with the usual casing II (Fig. 2) having a removable cover plate I2. This transmission will accommodate three forward gear ratios and one reverse gear ratio. The transmission per se includes a driving shaft I3 operatively connected to the crank shaft M of the motor vehicle engine I5 through a clutch mechanism designatedin its entirety at I6. The driven shaft I! of the transmission is piloted as at |-8- in the rear end of the driving shaft I3 and this driven shaft is adapted to be operatively connected to the drive wheels of the vehicle (not shown) with which the transmission is associated. A countershaft til is provided below the driven shaft I 1 and carries a gear 20 which meshes with a gear 2| mounted on the driving shaft I3, these two gears being in constant mesh with each other. The countershaft I9 is shown in Fig. 1 as being displaced 90 from its usual position below the driving shaft I3. The countershaft I9 also carries a gear 22 which is in constant mesh with a gear 23 mounted on a sleeve 24 which is rotatably disposed on the driven shaft IT. A hub 25 is fixed on the driven shaft I! and forms part of a speed shift and synchronizing device in the form of a positive dual clutch assembly designated in its entirety at 26. A sliding shift collar 21 having internal splines 28 meshing with external splines 29 formed on the hub 25 is designed for selective engagement with a series of teeth 33 provided on a hub 3| forming apart of the gear 2| or with a series of teeth 32 formed on a hub 33 forming part of the gear 23. It will be seen, therefore, that when the shift collar 21 is moved from its neutral position as shown in Fig. 1 to its extreme left-hand position, the internal splines 28. thereof will engage the teeth 30 of the hub 3| and operatively connect the gear 2| to the driven shaft IT to establish a direct drive from the driving shaft I3 to the driven shaft Il'. Similarly, when the shift collar 21 is moved to its extreme right-hand position so that the internal splines 28 thereof engage the teeth 32 on the hub 33 of the gear 23, this latter gear will be operatively connected to the driven shaft I! so that an intermediate gear ratio will obtain between the driving and driven shafts, the train of gearsfor effecting such gear ratio constituting the gears 2| and 20, the countershaft I9, gears 22 and 23, shift collar 21 and hub 25.

The electrical control mechanism comprising the present invention is adapted to automatically effect movement of th shift collar 21 to establish either an up-shift or a down-shift between second speed gear ratio and third or direct speed gear ratio as will be described hereinafter. However, the transmission I0 is capable of being shifted into a low speed gear ratio by a manual operation, if desired, and toward this end a gear 34 mounted on the countershaft I9 is capable of meshing with a gear 35 which is splined as at 36 to the driven shaft I1 and which is slidable axially of the latter into and out of engagement with the gear 34. The gear 35 is also capable of being placed in mesh with an idler gear 31 which meshes with a gear 38 mounted on the countershaft I9 to establish a revers speed gear ratio when occasion demands.

The transmission I0 just described is merely exemplaryof one form of transmission that may be employed for control by the mechanical and electrical instrumentalities which cooperate to make up the present invention, and it wilt be understood that other forms of transmissions having a shii'table member movable between two positions in opposite directions to effect an upshift and a down-shift are' contemplated. The transmission. IB- is operatively associated with the clutch mechanism Hi and this latter as-- sembly is preferably in the form of a centrifugal clutch which remains disengaged atrelatively low engine speeds and which is adapted to automatically become engaged when: a predetermined engine speed is attained.

The clutch diagrammatically shown in Fig; I is provided. with a housing 40 (Fig. 2 and in cludes a driven disc 4| carrying friction facings 42 and mounted on a hub 43 through a torque cushioning drive including. springs 44 The disc 4| is disposed between the rear face of the engine flywheel 45 and an axially movable pressure plate 46, which plateis advanced toward the flywheel to take up running clearances. and clamp the driven disc against the flywheel to transmit power therefrom to the clutch driven shaft I3. which forms the driving shaft of the transmission I0. The pressure plate 46: is backed by aspring mounting ring 4! which in. turn is backed: by a plurality of preloaded pressure springs 48... the total load of which determines the. maximum clutch engaging pressure. The ring 4! is normally held in the position shown in Fig. I by throw-out fingers 49 carried. on. mounting studs 50 and having links 51 connected. to the. mounting ring 41. The inner ends of. the fingers 4'5!- normally contact and follow a throw-out collar 52 slidable on a sleeve 5'3enveloping the shaft I3. The throw-out collar 52- is backed bya throw-out fork 54 (see also Fig. 4:) mounted on a shaft 55 and when the collar is. held in the posi tion of Fig. 1, it acts through the multiplying leverage of the throw-out fingers 49 to hold the mounting ring retracted.

A series of weights 56 are nested: within the mounting ring 47 and carry offset lugs 51 which are interposed between the pressure. plate and the mounting ring, these lugs passing through slots formed in the latter. The lugs 51 form fulcrums for the weights and bear against hardened steel inserts 58 on the pressure plate. Outward movement of the weights 56 due to contrifugal force acts to pry the pressure plate and mounting ring apart, the pressure plate: moving to the left until running clearances are taken up, after which additional outward. movement of the weights 56 causespressure to be. applied to the friction facings421of the disc 4| to force the friction, facings against the flywheel 45 and transmit the motion of the latter to the driving shaft I3 of the transmission Ill.

The above description of. the clutch mechanism I6 is suincient for descriptive purposes of this application. However, for a more detailed description: of the centrifugal clutch mechanism I6 reference may be had to the patent to Gamble, No. 2,070,892, dated February 16', 1937-, for an automatic clutch.

Upon rotation of the clutch at a. predetermined speed, the several weights; 56 will be thrown radially outward by centrifugal force, thus applying a force through the offset lugs 51 about their fulcrum points tending to pry the pressure plate 46 away from the spring mounting rings 41' and into contact with the driven disc 4|. After running clearances have been taken-up, the final portion: of? the outward swing of the weights acts to shift the spring mounting ring 41 to the right, transferring the pressure spring load to the pressure plate. The clutch I6 is shown in what is known as its idle released position wherein the pressure plate 46 and driven disc 4| present a slight clearance. In this position, the clutch is disengaged. Any movement of the pressure plate 46 to the left, whether it be by virtue of the centrifugal action of the weights 56 as previously described or whether it be by virtue of the throw-out fork 54, will tend to engage the clutch. The throwout collar 52 normally assumes the full line position shown in Fig. 1 and its movement to the right along the sleeve 53 is limited by the position of the throw-out fork 54. The throw-out fork 54 is fixed to the shaft 55 as previously described, and the shaft 55 has mounted thereon exteriorly of the clutch housing 40 (Fig. 2) a depending lever 59 having a pin and slot connection 60 with a link 61 pivoted as at 62 to the lower end 63 of the vehicle clutch pedal 64. The clutch pedal 64 is pivoted as at 55 to a bracket 66 suitably secured to the forward or outer side of the vehicle fioorboard 61. A finger 68 is pivoted at 69 to a bracket likewise secured to the forward side of the vehicle floorboard and is adapted to bear against one side of the clutch pedal 64 to limit its rearward movement to the position shown in full lines. With the clutch pedal 64 in this position, the lost motion of the link BI is completely taken up by the pressure of the collar 52 against the throw-out fork 54. The throw-out collar 52 is capable of slight movement to the right to the position thereof shown in dotted lines. The finger 68 is connected to one end of a Bowden wire assembly lI having associated therewith a manual control knob 12 positioned adjacent the instrument panel I3. The operator of the vehicle may move the control knob I2 in order to swing the finger 68 out of the path of movement of the clutch pedal 64, thus allowing the clutch pedal to move upwardly slightly to its dotted line position and in so moving, the link BI is moved slightly to the left to allow the throw-out fork 54 to release the throwout collar 52 and permit the latter to assume its dotted line position wherein the clutch is engaged under the influence of the springs 48. The clutch is then engaged while the centrifugal weights are inactive, thus permitting clutch engagement with a dead engine. In this condition of the clutch, it is possible to start the engine by pushing the vehicle.

It has been stated above shown in Fig. 1, the clutch may be said to be in its idle released position. By the term idle released is meant a condition of the clutch mechanism wherein the weights 56 are inactive and the clutch pedal 64 is released by the foot of the operator so that its movement is limited by the end of the finger 68. The positions of the spring mounting ring 41 and pressure plate 46 are such that the friction facings 42 do not quite touch the flywheel 45 and pressure plate 46 and therefore the clutch actually is disengaged, but is conditioned for immediate engagement when the accelerator pedal is depressed and the engine driving shaft I4 commences to accelerate to energize the weights 56.

It will be appreciated that whenever a transmission up-shift or down-shift is made, whether the shift be of a manual nature or whether it be an automatic shift in accordance with the principles ot; the presentinvention, it will be that in the position I necessary that the clutch I6 be disengaged inimediately prior to and'during a shift and that after the shift has been accomplished, in order for the same to take effect, the clutch will have to be re-engaged. According to the present invention, automatic disengagement of the clutch immediately prior to a gear shift operation and re-entry thereof after the gear shift operation has been completed is accomplished by mechanism best illustrated in Fig. 4.

Referring now to Fig. 4, the previously described throw-out fork 54 is keyed as at I4 to the shaft 55 and the upper end thereof normally bears against the throw-out collar 52. The shaft 55 also has loosely mounted thereon a rocker element 8|, the lower end of which is provided with an extension 82 adapted to bear against a finger 83 integrally formed on the shaft 55. The upper end of the rocker element 8| is provided with a notch 84 into which there extends the pointed end 85 of a thrust rod 86 which passes through an opening 81 formed in the front face of the transmission casing II and also through an opening 88 in the rear wall of the clutch housing 46. The rocker element 8I is provided with an offset extension 99, the extreme outer end of which is connected as at 96 to the plunger 9I of a one-way clutch re-entry dashpot assembly 92, the latter being anchored as at 93 to a bracket 94 suitably mounted on a portion of the clutch housing 49. The two openings in the rear wall of the clutch housing 49 and in the front wall of the transmission casing II are in alignment and a flexible diaphragm 95 secured to the thrust rod 86 and to the inner edge of the opening 81 provided in the front wall of the transmission casing I I serves to prevent egress of oil from the latter.

The clutch re-entry dashpot 92 is of the single acting type and is provided for the purpose of slowing down the re-engagement of the clutch after a transmission up-shift or a transmission down-shift has been effected. The dashpot assembly 92 is of more or less conventional design and includes an outer casing or cylinder 96 having slidably disposed therein a piston 91 integrally formed with the plunger 9I. The piston 91 is formed with a recess 98 therein in which there is disposed a ball valve 99 which normally rests by gravity on a retaining spider I011. The recess 98 communicates with a bore IOI which in turn communicates with the upper regions of the cylinder 96 above the piston 91. A bleeder port I02 extends through the piston 91. A suitable fluid I03 which may be oil is contained within the cylinder 96. From the above description of parts, it will be seen that substantially free movement of the piston 91 and plunger 9I upwardly may obtain, but downward movement of this iston and plunger assembly is restricted by the ball valve 99 which, when the piston moves downwardly, is forced against its seat within the recess 98 due to the action of the oil attemptin to pass through the recess 98 and bore I9 I, thus limiting the downward movement of the piston to that which is permitted by virtue of the oil passing through the bleeder port I02. It will also be seen that clutch disengagement by movement of the thrust rod 86 to the left as shown in Fig. 4 may be a rapid one while clutch re-entry operations are restricted by virtue of the action of the dashpot 92.

The other pointed end I04 of the thrust rod 86 extends into a notch I95 provided in a cam follower I66 which is pivoted on a stud I01 mounted interiorly of the transmission casing II.

The cam follower I06 carries a'roller I08 at its free end designed for cooperation with a clutch throw-out cam I09 mounted on and keyed to a cam shaft III} rotatably mounted in and carried by a motor drive and reduction gear unit or assembly designated in its entirety in Figs. 2, 3 and 5 at I20.

The motor drive and gear reduction assembly I20 is bolted to the transmission casing II, and includes casing sections I2 I and I22, the latter being provided with a cover plate I23. An electric motor M projects into the casing section I22 and is provided with a motor shaft I24 which projects through the casing section I 22 and has a gear I25 mounted thereon. The gear I25 meshes with a large gear I26 mounted on a shaft I2! ro tatably journaled in anti-friction bearings I28 and I29 carried by the casing sections I2I and I22 respectively. The gear I26 has integrally formed therewith a smaller gear I30 which meshes with a large gear I3I secured to the cam shaft IIO.

From the above description, it will be seen that the gears I25, I26, I30 and I3I constitute a gear reduction train whereby the speed of rotation of the motor shaft I24 is transmitted to the cam shaft I I at a greatly reduced rate of turning movement.

The cam shaft I I0 is rotatably supported with in the casing sections I 2I and I22 in anti-friction bearings I32 and I33, the former being disposed within a hub I34 on the casing section I2I and the latter being disposed wthin an internal web I35 formed in the casing section I22. A seal I36 prevents egress of oil from the transmission casing II into the interior of the motor drive and gear reduction assembly I20.

The motor M is preferably of the direct current shunt wound reversing type and, as will be described presently, is cyclicly. operable to rotate the cam shaft IIO successively throughout one complete revolution in opposite directions for the purpose of effecting alternate up-shifts and down-shifts of the transmission gearing.

Rotation of the cam shaft I I0 and consequently of the clutch cam I09 throughout substantially 360 in either direction causes an early clutch disengagement at the commencement of the shift cycle and a subsequent clutch re-entry operation toward the close of the cycle, as is customary duz'ring manual driver control of the vehicle utilizing the gear shift lever for the gear ratio changing operations.

Accordingly, the cam I09 is provided with a region of low eccentricity on one side thereof which merges in both peripheral directions into a region of high eccentricity. A region of lowest eccentricity is afforded by means of an arcuate groove I31 which, when the cam is in its normal position, occupies a position in close proximity to the cam follower roller I08 for purposes which will be made clear presently. The normal clutch spring mechanism employed in connection with the clutch proper including the spring 48 serves normally to urge the roller I08 of the cam follower toward the periphery of the cam and when this follower assumes the position shown in Fig. 4, the clutch I6 is in its idle released position when the engine I is idling or is engaged when the engine is operating above idling speed.

In the idle released position of the clutch as shown in Fig'. 1, the clutch pedal 64 bears against the end of the finger 6.9 and the solid clutch linkage leading from the finger 68 back through thethrust ro.d.8.,6 to the cam follower I06 causes the follower rollerv I08 to assume the position shown in Fig. 4 wherein it is out of engagement with the surface of the cam I09 but is capable of moving into engagement with this surface in the region of the groove I 31 when the finger 69 is withdrawn from the path of movement of the clutch pedal 64 by means of the Bowden wire II. This arcuate depression I31 permits the clutch to be fully engaged in the manner previously described for the purpose of permitting the engine to be started by pushing the vehicle. With the follower I06 in the position shown in Fig. 4, the clutch is in its idle released position providing, of course, that the rotational speed of the shaft I4 is insufficient to energize the weights 56. R0- tation of the cam I09 in a counter-clockwise direction as indicated by the outer arrow in this figure throughout approximately 120 serves to effect a gradual clutch disengagement, this disengagement being represented by the sector labeled cd. During movement of the cam from its point of low eccentricity to a point of high eccentricity wherein a surface of the cam 120 removed from the point of lowest eccentricity of the cam is in engagement with the roller I08, the cam follower is forced in a clockwise direction as shown in Fig. 4 to cause the thrust rod 86 to move to the left and rock the rocker element ill in a counter-clockwise direction and move the .extension 92, and consequently the finger 83., to thus cause the shaft to rotate in a counterclockwise direction. Upon such counter-clockwise rotation of the shaft 55, the throw-out fork 54 bears against the throw-out collar 52 and causes the same to move on the sleeve 53 to the left as shown in Fig. 4 and thus cause clutch disengagement in the manner previously described.

From the above description, it will be seen that during approximately the first of each upshif-t cycle, clutch disengaging operations ta'ke place. During the next succeeding one-third cycle of the gear shifting operations, the actual transmission shift takes place while the clutch remains disengaged by virtue of the cam roller I08 traveling upon a high region of the clutch cam I09 as represented by the sector designated de. During the last third of the gear shift cycle while the roller I08 travels on the sector e of the cam I09, clutch re-entry operations will take place by virtue of the roller I08 riding inwardly on a low portion of the cam I 09 and causing the follower arm I06 to move in a counter-clockwise direction, thus permitting the thrust rod .85 to move to the right to in turn permit the rocker element 8I and shaft 55 on which it is mounted to move in a clockwise direction. Such clockwise movement of the shaft 55 causes the throwout fork 54 to swing in a clockwise direction and permit backing off of the throw-out collar 52 and consequent clutch re-entry as previously described. During such clutch re-entry operations, the dashpot assembly 92 serves to retard the speed of such clutch re-entry operations.

As previously stated, the actual speed ratio changing operation to effect either an up-shift or a down-shift'by movement of the collar 21 (Fig. l) to the right or to the left, as the case may be, may be effected manually or it may be an automatic operation which occurs during a portion of the shift cycle while the clutch I6 remains disengaged. For manual shift operations the usual gear shift lever I50 is provided, this lever being capable of selective operation to control the shifting movements of the shift 11 collar 21 and of the shiftable gear 35 associated with the transmission I0.

Referring now to Figs. 1, 2 and 3, the side wall of the transmission casing II is provided with a pair of bearing bosses II, I52 through which the shaft portions I53, I54 of a pair of shifting crank arms I55 and I56 respectivelyextend. The crank arm I55 extends into a slot I51 (Fig. 3) provided in a cooperating crank arm I58 mounted on a transverse shaft I59 extending across the transmission casing. The crank arm I55 carries a shift fork I60 which cooperates with the shift collar 21. An operating lever I6I (Fig. 1) carried on the shaft portion I53 of the crank arm I55 controls the movements of the shift collar 21.

A shift fork I62, similar to the shift fork I60, cooperates with the shiftable gear 35 and derives its movements from an operating lever I63 similar to the lever I6I and carried on the end of the shaft portion I54 of the crank arm I56. The operating levers I6I and I63 are connected by a linkage mechanism subsequently to be described to the steering post control mechanism which includes the gear shift lever I 50.

An interlock device I64 permits the operating levers I6I and I63 to be shifted only one at a time. This device I64 includes a sector portion I65 on each of the crank arms I55 and I56, each sector having notches I66 formed therein for cooperation with a combined interlock and yieldable positioning poppet device I61 including a tube I68 mounted in a bore I68 formed in a boss I on the inside of the transmission casing II. A pair of balls I1I are mounted within the end regions of the tube and are engageable in the notches I66. The balls are yieldingly urged outwardly by means of a coil spring I12. Disposed between the ends of the coil spring I12 and the balls "I are a pair of abutments I13 having stems I14 extending inwardly toward each other within the confines of the spring I12. The stems I14 are of such length as to permit one of the balls I1I to ride upon a high region of its coacting sector so as to permit the corresponding crank to be oscillated for shifting one of the torque transmitting shafts. When engaged in a central notch, the ball will hold its corresponding crank in a neutral position, but when engaged in either of the side notches, the ball will yieldingly hold the crank in a position to establish a drive at a selected gear ratio through the transmission. When one of the cranks is being shifted, the corresponding ball will be moved inwardly as the high region of the sector rides against it and the stems I14 are of such length that they will then engage each other so as to form, together with the balls, an unyieldable column between the two sectors with the opposite ball centered in one of its coacting notches so as to prevent shifting of the other crank. Thus it is impossible to simultaneously shift both cranks. The notches I66 in the sector portions I65 are of such a nature that neither one of the torque transmitting shafts I53 or I54 can be moved from one position to another unless the other shaft is in its neutral position. For a more detailed disclosure of such an interlock device, reference may be had to the patent to Haigh, No. 2,350,506, dated June 6, 1944, for a transmission.

The invention contemplates the employment of a conventional type of control mechanism of such a character that when one of the shift levers I 6| or I63 is out of its neutral position 12 and consequently a certain gear ratio has been selected, it will be impossible for the linkage mechanism leading from the gear shift lever I50 to select the other operating lever for operation.

The operating lever I6I is provided with a notch I15 therein designed for cooperation with the operating finger I16 of a microswitch hereinafter referred to as the neutral switch Sn and which constitutes one of the electrical instrumentalities associated with the control system of the present invention. The neutral switch Sn is suitably secured to the transmission casing and for convenience, it is bolted to the bearing boss I5I through which the operating shaft I53 extends. When the transmission is in neutral, the lever I6I will assume a position wherein the operating finger I16 enters the notch I15 and a certain electrical circuit is conditioned 01' potentially established by the closing of certain contacts. Upon completion of the circuit by depression of the accelerator pedal, the primary coil of the ignition system of the vehicle becomes grounded in a manner that will be de scribed presently so that the engine is prevented from racing during that portion of a shift cycle when the clutch is disengaged. The neutral switch Sn also serves to prevent initiation of a gear shift cycle when the transmission is operating in low or reverse gear ratio.

The above-mentioned linkage which extends between the steering post control mechanism and the operating levers I6I and I63 is schematically shown in Fig. 1 and includes a rod I pivotally connected at one end to the lever I63 and a similar rod I8I pivotally connected at one end to the lever IBI. The other ends of the rods I80 and I8I are secured to respective slide members I82 and I83 which are disposed at different elevations below the steering post I84 of the vehicle and which are supported in guideways (not shown) for longitudinal fore and aft shifting movements. The shift lever I50 has its inner end secured to a central shift rod I85 which projects downwardly through the steering post I84 and which has secured thereto at its lower end an operating finger I86, designed for selective reception in a pair of notches I81 and I88 formed in the slide members I82 and I83, respectively. A coil spring I88 serves to maintain the shift rod I85 in its lowermost position with the finger I86 disposed within the notch I88 so that a clockwise movement of the shift lever I50 will move the slide member I83 rearwardly to rock the operating lever I6I in a counter-clockwise direction and shift the collar 21 to the left to establish a direct drive and so that a counterclockwise movement of the shift lever I56 will cause the slide member I83 to be moved forwardly to impart a clockwise movement to the operating lever I6I and cause the shift collar 21 to be moved to the right to establish second or intermediate speed gear ratio.

In order to shift the transmission into reverse or low gear ratio, the operator may elevate the shift lever I50 in the usual manner so that the finger I86 will project into the notch I81 and control the movements of the slide member I82 to efiect shifting of the gear 35 to establish a reverse or low speed gear ratio as desired in the manner previously indicated. The positions which the shift lever I50 must assume to obtain the various gear ratios of which the transmission is capable are indicated by legending in Fig. 1.

Where automatic gear shifting operations are resorted to, the present invention is concerned only with shifting movement of the slide member I83 between its two extreme positions wherein the transmission may be shifted between second speed gear ratio and high or direct gear ratio. Such automatic gear shifting operations are attained by virtue of the provision of a depending shift finger I90 (Figs. 3 and 4) which is mounted on the shaft I59 within the transmission casing I I and which projects downwardly within the casing alongside the clutch throw-out and re-entry cam I 09. The gear shift finger I90 is provided with a hub portion I9I through which the shaft I59 extends. A lost motion connection between the hub I9I and shaft I59 is provided by virtue of a pair of ears I92 which project into elongated slots I93 formed interiorly of the hub I9I l A lost motion take-up spring I94 is secured to a stationary lug I95 formed on the transmission casing and has its end projecting between a pair of ears I96 formed on the hub I9I. The purpose of the lost motion connection will become apparent presently.

A roller I9! is mounted on the cam I09 and the shift finger I90 is normally positioned directly in the path of movement of the roller so that as the cam I09 makes a complete counter-clockwise revolution, the roller I91 will engage one side of the depending shift finger I90 and cause the latter to be swung in .a clockwise direction to rotate the shaft I59 correspondingly and effect an up-shift from second speed gear ratio into third speed gear ratio. Similarly, upon rotation of the roller I97 in the opposite direction, it-will engage the other side of the shift finger I90 to cause the latter, together with the shaft I59, to be swung in a counter-clockwise direction to effect a down-shift from third speed gear ratio into second speed gear ratio. The lost motion connection between the hub I9I and shaft I59 is provided for the purpose of insuring that the gear shift finger I90 will at all times be positioned in the path of movement of the roller I91 at the commencement of a gear shift cycle whether the cycle be for an up-shift as represented by a counter-clockwise revolution of the cam shaft I I as viewed in Fig. 4, or for a downshift as represented by a clockwise revolution of the cam shaft H0. During the actual gear shift portion of the cycle when the roller I91 is in engagement with the side of the gear shift finger I90, the lost motion existing between the finger I90 and the shaft I59 is taken up. However, as soon as the finger I 90 is released by the roller I97, the spring I94 causes the finger I90 to move in a reverse direction throughout a few degrees of angularity as permitted by the lost motion connection so that the end region of the finger I90 will be positioned squarely in the path of the roller I 97 during the next succeeding shift cycle when the roller travels in an opposite direction.

In Fig. 4 the clutch throw-out cam I09 is shown in its normal between-cycle position of rest. The gear shift finger I90 is shown in full lines in the position it assumes when the transmission is in second speed .gearratio and the dotted line position of the finger indicates the position it .assumes when the transmission is in third speed gear ratio. It is to be noted that the axial center line of the roller I91 lies in a plane which bisects the angle formed by the two extreme positions of the gear shift finger I90 so that upon rotation of the clutch throw-gout cam I09 in either direction, theiarcuate distance traveled by the roller from its position of rest thereof.

'14 to'its position of initial contact with the gear shift finger I'will be the same. In other words, whether an up-shift'or a down-shift cycle takes place, the actual point in the cycle at whichgear shifting operations commence will remain the same and in either case, with respect to the clutch throw-out and re-entry operations, the same timing sequence will prevail. As illustrated in the timing chart of Fig. 8, clutch throw-out operations commence shortly after the cycle is initiated and are completed at approximately in the cycle. At this point, gear shift operations commence and these are completed at approximately 240 in the cycle whether the change in gear ratio be for an up-shiftor for a down-shift.

Immediately after the gear shift operation has been completed, clutch re-entry commences and this is completed at substantially 360 in th cycle.

Referring now to Fig. 3, the cover plate I23 of the gear reduction unit I20 has mounted thereon an inwardly projecting tubular member I98 on which there is rotatably mounted a motor reversing cam 99 which is designed for limited turning movement in opposite directions on the tubular member I98. The cam member I99 is frictionally held on the member I99 against free turning movement thereon and, toward this end, a corrugated washer 200 surrounds the member I98, and bears against the inner face of the cover plate I23. A second friction washer 20I surrounds the member I99 and bears against the corrugated washer 200 on one side thereof and against the reversing cam I99 on the other side The tubular member I98 is provided with an annular radial flange 202 against which the side of the reversing cam I99 bears so that this cam is frictionally held between the flange 202 and the side of the friction washer 20I, the latter being keyed as at203 to the tubular member I98.

A finger204 is formed on and projects latterly from the periphery of the reversing cam I99 and is positioned in the path ofmovement of a similar-finger 205 formed on a'disc 206 which is keyed to and rotatable with the cam shaft H0.

As shown in Fig. 6, the reversing cam I99 is provided with an elevation 291 designed for cooperation with the operating finger 208 of a microswitch Sr which constitutes a reversing switch for reversing thepolarity of the field windings of the motor M to effect reversal of movement of the cam shaft I I0 as will be described when the electrical features of the invention are discussed. The finger 205 is angularly disposed on the cam shaft H0 in such a manner that at the end of each shift cycle representing an upshift from second speed gear ratio to third speed gear :ratio, the finger 208 will ride outwardly upon the elevated portion 20'! andremain there until the next succeeding down-shift cycle takes place. Similarly at the end of each down-shift cycle the finger 208 is adapted to ride inwardly of the cam I99 onto the .lower regionsthereof. As shown in Fig. '7, thereversing switch Sr is of the double throw double contact type and is possessed of a pair of #1 contacts and a 'pair'of #2 contacts adapted to be alternately closed by a pivoted arm 209 to effect a reversal of polarity through the field windings of the motor at the end of each shift cycle of operation of the mechanism. I i I I 1 Referring now to Figs 3- and 5, an interrupter cam 210is keyed to'the camshaft .I lfland'is thus rotatable therewith'in opposite directions. This cam 2l0 is provided with a high portion 2 and low portion 2 l 2 which cooperate with the operating finger 2 [3 of a microswitch assembly Si similar in its construction to the switch Sr and likewise having #I and #2 contacts. The switch Si constitutes an interrupter switch, the function of which will become apparent when the circuit diagram of Fig. '7 is discussed.

Referring now to the circuit diagram of Fig. '7, a number of electrical and other instrumentalities have been shown in their proper electrical relationship and cooperate with one another in carrying out the principles of the invention so that voluntary or involuntary gear shift operations will take place in accordance with the principles of the invention.

The operator of a vehicle equipped with the control mechanism of the present invention is confronted with very little that is unfamiliar to the average driver. Although the need for them is largely eliminated, the standard gear shift lever I53 and the usual clutch pedal may be retained in the vehicle and may be used in the conventional manner to accomplish their normal functions when desired.

A selector switch Ss is provided and this switch may b located at any suitable point within the vehicle where it is accessible for manual manipulation by the driver as, for example, on the steering column or on the instrument panel 13 of the vehicle. The previously described neutral switch Sn which is secured to the boss 5| (see Fig. 1) surrounding the torque transmitting shaft I53 operates when the transmission is in neutral, low or reverse drive to demobilize the entire electrical control system of the present invention.

A governor switch Sg operates under the control of a governor 2M associated with the out put or driven shaft I! of the transmission. Under a pre-determined vehicle speed of approximately miles per hour, the #2 contacts of this switch are adapted to remain closed while over this vehicle speed, these #2 contacts become open and the contacts thereof become closed. The #3 contacts of the governor switch Sg remain closed under a vehicle speed of approximately miles per hour and are adapted to become opened when this vehicle speed is exceeded. The governor switch Sg is also provided with a pair of #4 contacts which, when an overdrive mechanism is employed in connection with the transmission I0, form a part of the standard overdrive electrical circuit.

Referring now to Figs. 1 and 7, an accelerator switch So. is provided and includes normally closed #1 contacts and normally open #2 and #3 contacts. This switch may be located on the vehicle floorboard 61 and is adapted to be operated under the control of the usual accelerator pedal 2l5. It will be seen from an inspection of Fig. 7 that upon depression of the accelerator pedal M5, the normally closed contacts of the switch Sa are adapted to become opened and the normally open #2 and #3 contacts are adapted to become closed. In Fig. '7 the accelerator is shown as being depressed against the influence of a spring 2l6 with the contacts thereof open and the #2 and #3 contacts thereof closed.

Referring now to Fig. 1, the vehicle engine I5 is provided with the usual carburetor designated in its entirety at 220 andhaving a pivoted butterfly valve 22I associated therewith, this valve being shown in its fully closed position with the accelerator pedal 2l5 being released. The valve 22! is adapted to be operated under the control of a link 222 having a lost motion connection 223 with the butterfly valve 22l and a ball and socket joint 224 with the accelerator pedal 2l5. A throttle dashpot assembly designated in its entirety at 225 operates to retard closure of the butterfly valve 22! to prevent th engine from decelerating too rapidly during the interval of time existing when the clutch I6 is disengaged during a transmission up-shift or a transmission down-shift so that the engine will not act initially as a brake on the vehicle and cause an objectionable negativ lurch at the commencement of a shift cycle. The dashpot 225 is of the single acting type and may have a mechanical arrangement similar to that described in connection with the clutch re-entry dashpot assembly 92.

A brake switch Sb (Fig. 7) is provided and is of the normally closed type, but it i adapted to become open when the brake pedal 225 of the vehicle is depressed.

A reversing switch Sr having it! and #2 contacts is adapted to become reversed near the end of each shift cycle to condition the control system for a down-shift when an up-shift has just been completed and vice versa.

An interrupter switch Si having its #1 contact normally closed and its #2 contacts normally open is adapted to become reversed at predetermined points in the gear shift cycle as will be explained presently. A circuit breaker GB is also provided and may be located on the dashboard of the vehicle or in any suitable convenient location.

A plurality of relay magnets and their associated relay contacts are provided and may be enclosed within a casing (not shown) mounted at a convenient location on the vehicle as, for example, on the side of the vehicle transmission casing ll. These magnets include an lip-shift magnet Ru having #I and #2 contacts, a downshift magnet Rd likewise having #I and #2 contacts and an interrupter magnet Ri having a single pair of contacts 250.

Current is supplied to the control system from the usual automobile battery B of Fig. 7 through the circuit breaker CB. If the transmission is assumed to be in second speed gear ratio and the car to have been accelerated above the speed for which the #1 and #2 contacts of the governor switch Sg are set, release of the accelerator pedal 2; will close the #1 contacts of the switch Sa, thus calling for an up-shift of the transmission from second speed gear ratio to third speed gear ratio. Current will flow from the positive side of the battery through a lead 252, selector switch Ss (now closed), lead 253, #2 contacts of the neutral switch Sn, leads 254, 255, contacts of the governor switch so (now closed), lead 256, contacts of the accelerator switch Sa (closed by virtue of release of the accelerator pedal 215), lead 251, normally closed brake switch Sb, leads 258, 259, #1 contacts of the reversing switch Sr (now closed), lead 260, up-shift relay magnet Ru, and lead 26| to the negative side of the battery.

Completion of the circuit just described causes energization of the up-shift magnet Ru and clo sure of the #2 contacts thereof whereby a circuit is completed through the field winding 26! of the motor M. This circuit exists from the positive side of the battery B through lead 252, selector switch Ss, leads 262, 253, #2 contacts of the up-shift magnet Ru (now closed), leads 264, 265, 256, field winding 261 of the motor M, lead 268, contacts of the down-shift relay magnet Rd, lead 269 to the negative side of the battery. A one-way blocking device or rectifier 219 prevents short-circuiting of the field winding 261 of the motor M. Current may pass through the one-way blocking device or rectifier 21! to energize the interrupter magnet Ri. The circuit for this latter magnet exists from the battery B through lead 252, selector switch S8, leads 262, 263, #2 contacts of the up-shift magnet Ru (now closed), leads 264, 212, rectifier 21!, lead 213, interrupter magnet Ri, lead 214, contacts (closed at this point in the cycle) of the interrupter switch S2, and lead 215 to the negative side of the battery. Energization of the interrupter magnet R2 causes closure of its contacts 259, thus establishing a direct circuit for the relatively heavy armature current of the motor M. This circuit leads from the battery B, through lead 216, contacts 250, lead 211, armature 218 of the motor M and lead 219 to the negative side of the battery. Since both the field winding 261 and armature 218 of the motor M become energized as described above upon completion of their respective circuits, the motor armature commences to rotate in such a direction as to cause the cam shaft I10 to rotate in a counter-clockwise direction as viewed in Fig. 4 to initiate an up-shift cycle.

At the commencement of the up-shift cycle, the clutch throw-out cam I09 commences to rotate in a counter-clockwise direction as viewed in Fig. 4 and as may be determined from the timing chart of Fig. 8, urging the follower 06 in a clockwise direction as viewed in Fig. 4, thereby disengaging the clutch E6 in the manner previously described. After the cam has rotated approximately 120 the clutch becomes fully disengaged but the actual gear shifting operations have not yet commenced to take place. At this position of the cam shaft I w the interrupter cam 2 i 9 has moved to a position wherein the #2 contacts of the interrupter switch S2 become closed and the contacts thereof become opened. It may be assumed at this point that the operator has again depressed the accelerator pedal 2L3 to accelerate the vehicle and, as a consequence, the #l contacts of the accelerator switch Sc have become open. Such opening of the contacts.

of this switch serves to open the previously described circuit through the up-shift magnet Ru but this magnet remains energized under the influence of a holding circuit which was established upon initial energization thereof. This holding circuit exists from the field winding 261' of the motor M through leads 265, 280-, rectifier 28!, leads 282, 259, contacts of the reversing switch Sr (now closed), lead 269, magnet Ru and lead 26-! to the negative side of the battery.

The up-shift magnet Ru thus remains energized and is unaiiected by reversal of movements of the neutral switch Sn, the. governor switch $9, the accelerator switch Sa, or the brake pedal switch Sb.

As previously stated, due to movement of the cam shaft H9 in a counter-clockwise direction as viewed in Fig. 4 and consequent rotation of the interrupter cam 216, the #2 contacts of the interrupter switch Si become closed and the #1 contacts thereof become opened. Closure of the #2 contacts of the interrupter switch S2 servesv momentarily to place the winding of theinterrupter magnet Ri in series with the armature of the motor M, this circuit leading from the battery B through lead 252, selector switch Ss, leads 262, 263, #2 contacts of theupshift magnet Ru, leads 264, 212, rectifier 21l, lead 213, magnet R2, lead 214, #2 contacts of the interrupter switch Si, resistance R, armature 218 of the motor M, and lead 219 to the negative side of the battery. With the #2 contacts of the switch S2 thus closed, the interrupter magnet R2 and its contacts 250 operate in the manner of a vibrator to intermittently interrupt the direct flow of heavy armature current through the motor M to cause the motor to operate at reduced speed and slow down the gear shifting operations and efiect a smoother shift. With the #2 contacts of the switch S2 closed and with the contacts 250 also closed, a circuit exists which shunts the interrupter magnet R1, thus causing the latter to become deenergized to permit the contacts 250 to become opened.

The resistance R together with the resistance of the winding of the magnet Rz' greatly restricts the flow of current through the armature of the motor and leaves insufiicient current to operate the motor. the field winding 261 of the motor still exists, the motor commences to operate in the manner of a generator to induce a voltage counter to or opposite in polarity to the line voltage in the magnet circuit. The voltage applied in this circuit is therefore the difference between the line voltage and the opposing motor generated voltage. At high motor speeds the difference is small, and is insufii-cient to energize the magnet Ri. However, as the motor speed falls off by virtue of the motor coasting with a decelerating motion, the voltage diiierential applied to the magnet Ri increases until, at a definite motor speed, it is suflicient to again energize the magnet Ri through the circuit previously described. As soon as this happens, the contacts 250 again become closed and full line voltage is again applied to the motor armature to bring the motor back to full power operation. Reclosure of the contacts. 259 again places a shunt around the winding of the magnet R2 and the entire process is repeated with the net result that the motor operates intermittently and consequently at reduced speed during actual gear shift operations. It will be seen that by varying the value of the resistance R, the speed to which the motor must fall before sufiicient voltage differential exists across the magnet coil to close the contacts 259 may be varied.

Referring now to Fig. 9, one form which the interrupter relay magnet R2 and its contacts 250 may assume has been illustrated although it will be understood that other forms of a satisfactory relay construction may be resorted to while still maintaining an operative structure. The magnet casing 299 is generally of cup-shape design and is provided with a cover plate 29 i. The magnet coil 292 is disposed within the casing 299 adjacent the bottom thereof and has slidably mounted therein a plunger or core 293. Energization of the coil 292 causes the plunger 293 to be drawn downwardly within the body of the coil 292 against the action of a coil spring 294-. The plunger 293- carries an insulating disc 295 having mounted thereon a contact plate 296 which is adapted, upon energization of the magnet and consequent retracting of the plunger 293 into the coil 292, to engage and electrically connect a pair of contact elements 291 carried at opposite sides of the magnet casing 290. The contact elements 291 together with the contact However, since the circuit through plate 296 constitute the electrical contacts 259 shown in the circuit diagram of Fig. 7. The plunger 293 is provided with a reduced extension 299 carrying a washer 299 at its outer end and a second spring 399 at one end thereof bears against the washer 299 and the other end thereof bears against the insulating disc 295, thus normally causing the plunger 293 to bear against the disc 295. The rate of the spring 399 is greater than the rate of the spring 294 or, in other words, the former spring presents a greater resistance to compression than the latter one so that upon energization of the coil 292 and consequent downward movement of the plunger 293, the spring 294 will first become compressed until such time as the contact plate 296 makes initial contact with the contact elements 291, after which further downward movement of the plunger 299 will cause compression of the spring 399. Upon deenergization of the coil 292, the plunger 293 is first urged upwardly by the spring 399 until such time as the plunger engages the disc 295 after which time the spring 294 urges the entire plunger assembly upwardly to open the contacts 259.

From the above description of parts, it will be seen that the relay magnet R2 has been designed to accommodate a steady fiow of heavy armature current through the motor circuit during those portions of the gear shift cycle wherein clutch throw-out and re-entry operations take place and which occur, roughly speaking, during the first and last third of the machine cycle as shown in the timing chart of Fig. 8. During these portions of the cycle, contacts 259 are adapted to remain continuously closed and in order to insure passage of the full armature current through these contacts without arcing, the spring 399 being fully compressed exerts a powerful influence on the contact plat 299 and forces the same against the contact elements 291 with considerable pressure. During the intermittent action of the relay magnet which occurs, roughly speaking, during a second third of the machine cycle, such a positive sealing action of the contacts 259 is not required and the full force of the spring 399 is not impressed on the contact plate 296, although plunger inertia and gravity have some efiect on the pressure which is applied to the plate 299 by the spring 399. In the operation of the relay magnet R2, the initial magnetic pull on the plunger 293 causes the air gap indicated at 39I to be reduced so that the magnetic pull increases rapidly causing the plunger 293 initially to move downwardl against the action of the spring 294 and finally to move downwardly still further against the action of the spring 399 to efiect the sealing action of the contacts 259 as outlined above.

After the gear shifting operation has been completed and the shift finger I99 has been moved by the roller I91 to its limiting position and has been released by the roller I91 to permit the spring I94 t take up the lost motion connection between the finger I99 and the shaft I59, which condition of parts takes place near the end of the second third of the machine cycle, the motor continues to operate but the interrupter cam 2I9 reverses the interrupter switch Si so that the #I contacts thereof become closed and the #2 contacts thereof becom opened, thus removing the resistor R from the magnet circuit and connecting the magnet directly across the battery terminals through the circuit previously described. The contacts 259 thus remain closed continuously and a steady flow of current through the motor armature obtains so that the motor rapidly resumes its full speed operation.

At this time clutch re-entry operations commerce and the cam I99 continues to rotate and the follower I96 moves inwardly toward the axis of the cam under the control of the dashpot assembly 92.

During a complete clockwise revolution of the cam I99 and the cam shaft II9 as seen in Fig. 6, the finger 295 leaves the cooperating finger 294 of the reversing switch cam I99 and, toward the end of a complete revolution of the cam I99, it engages the other side of the finger 294 and drives the cam I99 clockwise against the frictional resistance of the friction instrumentalities 299, 29I. The switch-operating finger or actuator 298 thus moves outwardly on the cam I99 and operates the reversing switch so that the #I contacts thereof open, and the #2 contacts thereof close. This opening of the #1 contacts opens the previously described holding circuit through the up-shift relay magnet Ru. De-energization of the magnet Ru serves to open the #2 contacts and close the contacts thereof, thus opening the circuit through the field winding of the motor M and also opening the circuit passing through interrupter magnet R2. Upon deenergization of this latter magnet, the contacts 259 thereof open to interrupt the flow of current through the motor armature 218. With the flow of current through the field winding 26'! and armature of the motor M discontinued, the action of the motor is rapidly brought to a standstill by the action of the friction instrumentalities which cooperate with the reversing switch cam I99 as previously outlined.

The only flow of current then existing in the electrical controls illustrated in Fig. 7 is the flow of current through the ignition system, the circuit extending from the battery B through lead 392, the primary winding 393 of the ignition coil, leads 394, 395, distributor contacts 396 and lead 39! to the negative side of the battery.

The down-shift cycle from third speed gear ratio to second speed gear ratio is similar to that just described with the exception that the cam shaft II9 rotates in a clockwise direction as seen in Fig. 4 causing the roller I91 to move the shift finger I99 to the right. As soon as the governor 2I4 falls below the speed for which it has been set, which may be approximately 10 miles per hour, the contacts of the governor switch Sg become open and the #2 contacts thereof become closed, thus establishing a circuit from the battery B through lead 252, selector switch Ss, lead 253, #2 contacts of the neutral switch (now closed), leads 254, 255, #2 contacts of the governor switch Sg, leads 398, 399, #2 contacts of the reversing switch Sr (now closed), lead 3I9, down-shift magnet Rd, lead 3I I, #3 contacts of the governor switch S9 and lead 3I2 to the negative side of the battery. Energization of the down-shift magnet Rd serves to open the contacts thereof and close the #2 contacts thereof, thus establishing a circuit through the field winding 26'! of the motor M leading from the battery B through lead 252, selector switch S3, lead 262, #2 contacts of the down-shift relay magnet Rd, lead 268, field winding 261 of the motor M, leads 266, 265, 264, and contacts of the up-shift magnet Ru (now closed) to the negative side of the battery. Upon energization of the down-shift magnet Rd, a. holding circuit is established for this magnet 21 extending from the field winding of the motor M, lead 3l3, one-way device or rectifier 3M, leads 3l5, 309, #2 contacts of the reversing switch Sr (now closed), lead 3H3, magnet Rd, lead 3, #3 contacts of the governor switch Sg, and lead 312 to the negative side of the battery.

The automatic down-shift just described will take place whenever the vehicle speed falls below the predetermined setting of the #2 contacts of the governor switch S9 regardless of the position of the accelerator pedal 2l5. This is an automatic shift which is independent of any voluntary action on the part of the driver. If at the time of such a down-shift the accelerator pedal is depressed and the throttle is fairly wide open, the engine will tend to race during that portion of the shift cycle when the clutch becomes disengaged. Additionally, upon re-engagement of the clutch, a positive lurch of the vehicle forwardly due to the inertia of the engine is apt to result. Both of these objectionable phenomena are corrected by the present invention by means which will now be described.

t will be seen that the contacts of the neutral switch Sn become closed whenever the transmission is in its neutral condition by virtue of the finger H6 entering the notch I15 formed in the operating lever Hil. One of the #I contacts of the neutral switch Sn is connected di-- rectly to the negative side of the battery through a lead 3l6 while the other #I contact is connected through the #3 contacts of the accelerator switch Sa to the primary ignition coil 303 of the vehicle ignition system. Thus, if the accelerator pedal 2l5 is depressed to substantially its open throttle kickdown position so as to close the #3 contacts, at the time the transmission assumes its neutral condition during downshift from third speed gear ratio to second speed gear ratio, the primary ignition coil 303 will be grounded through a circuit leading from this coil through leads 30 i, 3, #3 contacts of the switch so, leads 3l8, 3I9, contacts of the switch Sn, and lead 3 I 6 to the negative side of the battery. No backward lurch of the vehicle is encountered due to ignition interruption because the clutch is disengaged at the time the ignition becomes grounded. No ignition interruption will occur during an up-shift from second speed gear ratio to third speed gear ratio inasmuch as the ac,- celerator pedal 2I5 must be released in order to initiate the shift. The #3 contacts of the switch Sa therefore, being open, no circuit from the primary ignition coil 303 to the negative side of the battery is in efiect. If the driver signals for an up-shift by releasing the accelerator pedal M and then immediately depresses the pedal and closes the #3 contacts of the switch Sa, ignition interruption will take place, thus preventing the engine from racing during the actual gear shifting portion of the cycle.

In order to obtain a voluntary shift or kickdown from third speed gear ratio to second speed gear ratio when the accelerator pedal 2l5 is fully depressed, the #2 contacts to the accelerator switch Sc are provided. These contacts are adapted to become closed whenever the accelerator is depressed to or beyond wide open throttle position, and their function is to place a shunt around the #2 contacts of the governor switch Sg. After the vehicle has become accelerated above the speed for which the governor 2 I4 is set, the #5 contacts of the switch So are closed and the #2 contacts thereof become open. Thus, with the #2 contacts of the switch Sa closed by virtue of depression of the accelerator pedal 2I5, a circuit exists from the battery B through lead 252, selector switch Ss, lead 253, contacts of the neutral switch Sn, lead 254, #2 contacts of the switch Sa, leads 32B, 308, 309, #2 contacts of the reversing switch Sr (now closed), lead 3H5, downshift magnet Rd, lead 3, #3 contacts of the governorswitch So and lead 312 to the negative side of the battery. After such a voluntary shift or kickdown from third speed gear ratio to second speed gear ratio has taken place, an automatic upshift to third speed gear ratio will take place when the accelerator pedal 215 is released to close the contacts of the accelerator switch Sc through the normal upshift circuit passing through the magnet Ru as previously described.

While employing the engine for braking purposes in second speed gear ratio as, for example,

when descending a steep grade, it is desirable to prevent an automatic upshift when the speed of the governor 2M is exceeded. Otherwise, a sudden loss of engine braking will be experienced at an unexpected moment. To prevent this, the brake switch Sb is provided and is inserted in series with the accelerator switch Sa in the upshift circuit. The contacts of the switch Sb are adapted to become open whenever the brake pedal 226 is applied to open the normal circuit through the upshift magnet Ru. When the descent has been accomplished and braking is no longer required, an upshift to third speed gear ratio may be attained merely by releasing the brake pedal.

A voluntary downshift or kickdown from third speed gear ratio to second speed gear ratio is not eifective in providing increased acceleration at vehicle speeds exceeding approximately 25 miles per hour. For this reason, it is desirable to prevent such a kiclrdown when the vehicle is traveling at these relatively higher speeds. Whereas the #I and #2 contacts of the governor switch 89 are set so that they may be shifted at vehicle speeds of approximately 10 miles per hour, the #3 contacts of this switch are set to become opened whenever the vehicle exceeds approximately 25 miles per hour. These #3 contacts of the governor switch So are placed in the downshift circuit passing through the downshift magnet Rd and, while they may be placed at any suitable location in this circuit, they are preferably placed in the line leading from the downshift magnet directly to the negative side of the battery. Obviously, when these contacts are opened at vehicle speeds above 25 miles per hour, it is impossible to complete the downshift circuit through the downshift magnet Rd.

Where an overdrive is employed in connection with the transmission of the present invention, the pair of #4 contacts are associated with the governor 2M and form a part of the standard overdrive control circuit so that kickdown from overdrive to third speed gear ratio will be effected upon depression of the accelerator pedal H5 at high vehicle speeds as, for example, at miles per hour without afiecting any of the electric controls of the present invention.

It has been stated above that whenever an automatic shift is made, either involuntarily by virtue of driving conditions or as a voluntary act on the part of the driver as, for example, when he resorts to a throttle kickdown from third speed gear ratio to second speed gear ratio, the manual gear shift lever moves correspondingly, that is, if the transmission shifts automatically from second speed gear ratio to third speed gear ratio,

the gear shift lever I50 moves from second speed to third speed position. This phenomenon is desirable inasmuch as the driver will always be made aware of the particular gear ratio at which the transmission operates and should he desire to make a manual shift, he need only manually disengage the clutch I6 and move the gear shift lever I50 to a selected position providing, of course, a shift cycle is not in progress.

The motor reduction gearing I25, I26, etc., is made reversible, i. e., it is capable of being turned either by torque applied by the motor or by torque applied to the cam shaft IIO. This is desirable so that in the event of electrical control failure, the driver will not find the vehicle in a condition where the clutch is permanently disengaged with no ready means for re-engaging it. Reversible gearing, designed according to suitable engineering exigencies, and proper designing of the contour of the cam I09 eliminates the possibility of such permanent clutch disengagement.

An example of such gear train reversibility may be had by reference to Fig. 3. If it is supposed that failure of the electrical system occurs When the follower roller I08 is on the high circular arcuate portion of the cam somewhere within the confines of the sector de when the upshift is in progress thus holding the clutch I6 disengaged, the clutch cannot be re-engaged because insufiicient torque can be applied to the cam by the roller I08. If now the driver urges the manual gear shift lever I50 toward second gear position, the shift finger I90 will exert a force on the roller I9! tending to move the cam I09 in a clockwise direction as viewed in Fig. 4. Since the gear reduction train is reversible, the cam I09, all the gears of the reduction train, and the motor will rotate to a position wherein the roller I9'I separates from the finger I90. In this position the roller I08 is no longer on the high circular arcuate portion of the cam I09, but is on the downward slope. Thus, the pressure springs 48 of the clutch mechanism I6 (Fig. 1) may now react back through the cam follower I06 to apply continued clockwise torque to the cam I09. The clutch I6 thus becomes reengaged and the vehicle is left in a condition where the car may be driven manually in the customary manner of vehicle operation.

In order to avoid a dead spot through which torque cannot be applied to the cam I09 either manually or through the shift finger I90, or by the pressure of the clutch springs 48 through the cam follower I06, the cam I09 has been designed with a contour which requires the follower roller I08 to move on to the sloped portion of the cam at a point in the gear shift cycle in advance of the time that the roller I9! is out of the influence of the shift finger I90. As shown 1 in the timing chart of Fig. 8, there is a slight rise of the throw-out cam I from that portion of the cycle existing between 120 and 180 and there is a slight decline of this cam from that portion of the cycle existing between 180 and 240.

While I have described my invention in connection with one specific embodiment thereof, it is to be understood that this is by way of illustration and not by way of limitation and the scope of my invention is defined solely by the appended claims which should be construed as broadly as the prior art will permit.

I claim:

1. In a system including an internal combustion engine, a transmission mechanism connected to said engine and including a driving shaft and a driven shaft, means interposed between said shafts and operative to couple the former to the latter at various speed ratios and including a gear shift element movable in one direction to effect a transmission up-shift and movable in the opposite direction to effect a transmission downshift, a normally closed throttle valve for controlling the power supplied by said engine, electrical means controlling the displacement of said gear shift element, said electrical means being operable when the speed of said driven shaft falls below a predetermined speed to move said gear shift element in one direction and effect a transmission down-shift, said electrical means being operable when the speed of said driven shaft exceeds said predetermined speed and said throttle valve is substantially closed to move the gear shift element in the opposite direction and effect a transmission up-shift, and speed controlled switch means responsive to the speed of the driven shaft when the speed of said driven shaft exceeds a predetermined speed higher than said first-mentioned predetermined speed for rendering said electrical means inoperative to move said gear shift element to prevent a transmission down-shift.

2. In combination, a transmission including a driving shaft and a driven shaft, means interposed between said shafts and operable to couple the former to the latter at various speed ratios and including a gear shift element movable in one direction from one extreme position to another extreme position and through a neutral position to effect a transmission up-shift and movable in the opposite direction from said latter extreme position through said neutral position to said first extreme position to effect a transmission down-shift, cyclicly operable electrical means controlling the displacement of said gear shift element, said electrical means being operable when the driven shaft exceeds a predetermined speed to initiate a shift cycle and move said gear shift element in a direction to effect a transmission up-shift and being operable when said driven shaft falls below a predetermined speed to initiate a shift cycle and move the gear shift element in the opposite direction to effect a transmission down-shift, control means adapted when moved to a certain position to render said electric means inoperative to initiate a shift cycle, and a member movable with said shift element, said member acting to move said control means to said certain position when said shift element is moved to neutral position and out of said certain position when said shift element is in either of said extreme positions.

3. In combination, a transmission including a driving shaft and a driven shaft, means interposed between said shafts and operable to couple the former to the latter at various speed ratios and including a gear shift element movable in one direction from one extreme position to another extreme position and through a neutral position to effect a transmission up-shift and movable in the opposite direction from said latter extreme position through said neutral position to said first extreme position to effect a transmission downshift, cyclicly operable electrical means controlling the displacement of said gear shift element, said electrical means being operable when the driven shaft exceeds a predetermined speed to initiate a shift cycle and move said gear shift element in a direction to effect a transmission up-shift and being operable when said driven shaft falls below a predetermined speed to initiate a shift cycle and move the gear shift element in the opposite direction to effect a transmission down-shift, means operable when said gear shift element is in its neutral position prior to initiation of a shift cycle for rendering said electrical means inoperative, and means operable after commencement of a shift cycle for rendering said last-mentioned means ineffective during movement of the gear shift element through its neutral position.

4. In a system including an internal combustion engine, a transmission mechanism connected to said engine and including a driving shaft and a driven shaft, means interposed between said shafts and operative to couple the former to the latter at various speed ratios including an intermediate speed ratio and a high speed ratio and including a gear shift element movable in one direction to effect a transmission up-shift between said specified ratios and movable in the opposite direction to effect a transmission downshift between said specified ratios, a normally closed throttle valve for controlling the power supplied by said engine, cyclicly operable electrical means controlling the displacement of said gear shift element, said electrical means being operable when the speed of the driven shaft falls below a predetermined speed to initiate a shift cycle and move said gear shift element in one direction and effect a transmission down-shift between said specified gear ratios, said electrical means being operable when the speed of said driven shaft exceeds a predetermined speed and said throttle valve is substantially closed to initiate a shift cycle and move said gear shift element in the opposite direction and effect a transmission upshift between said specified gear ratios, and means operable when said transmission assumes a gear ratio other than said specified gear ratios for rendering said electrical means inoperative.

5. In a system including an internal combustion engine provided with an ignition circuit, a transmission mechanism connected to said engine and including a driving shaft and a driven shaft, means interposed between said shafts and operative to couple the former to the latter at various speed ratios including an intermediate speed ratio and a high speed ratio and including a gear shift element movable in one direction from an extreme position through a neutral position to another extreme position to effect a transmission up-shift between said specified ratios and similarly movable in the opposite direction through a neutral position to effect a transmission downshift between said specified ratios, a normally closed throttle valve for controlling the power supplied by said engine, cyclicly operable electrical means controlling the displacement of said gear shift element, said electrical means being operable when the speed of said driven shaft exceeds a predetermined speed and said throttle valve is substantially closed to initiate a shift cycle and move said gear shift element in one direction and effect a transmission up-shift between said specified gear ratios, said electrical means being operable when the speed' of the driven shaft falls below a predetermined speed to initiate a shift cycle and move the gear shift element in the opposite direction and effect a transmission down-shift between said specified gear ratios, means operable when said transmission assumes a gear ratio other than said specified gear ratios for rendering said electrical means inoperative, and means operable at the commencement of a down-shift cycle for rendering said ignition circuit inoperative during movement of said gear shift element through its neutral position.

6. In a system including an internal combustion engine provided with an ignition circuit, a transmission mechanism connected to said engine and including a driving shaft and a driven shaft, means interposed between said shafts and operative to couple the former to the latter at various speed ratios including a relatively low speed ratio and a relatively high speed ratio, said means including a gear shift element movable in one direction from an extreme position through a neutral position to another extreme position to effeet a transmission down-shift between said specified gear ratios, a reversible electric motor controlling the displacement of said gear shift element and means operable during movement of said gear shift element through its neutral position during a transmission down-shift for rendering said ignition circuit inoperative.

'7. In a system including an internal combustion engine provided with an ignition circuit, a transmission mechanism connected to said engine and including a driving shaft and a driven shaft, means interposed between said shafts and operative to couple the former to the latter at various speed ratios including an intermediate speed ratio and a high speed ratio and including a gear shift element movable in one direction from an extreme position through a neutral position to another extreme position ,to effect a transmission down-shift from said high speed ratio to said intermediate speed ratio, a reversible electric motor controlling the displacement of said gear shift element and means operable during movement of said gear shift element through said neutral position during a transmission down-shift for rendering said ignition circuit inoperative.

8. In a system including an internal combustion engine provided with an ignition circuit, a transmission mechanism connected to said engine and including a driving shaft and a driven shaft, means interposed between said shafts and operative to couple the former to the latter at various speed ratios including a relatively high speed ratio and a relatively low speed ratio, said means including a gear shift element movable in one direction from an extreme position through a neutral position to another extreme position to effect a transmission down-shift from said high speed ratio to said low speed ratio, cyclicly operable electrical means controlling the displacement of said gear shift element, said electrical means being operable when the speed of the driven shaft falls below a predetermined speed to initiate a shift cycle and effect a transmission down-shift from said high speed ratio to said low speed ratio, means operable when said transmission assumes a gear ratio other than said specified gear ratios for rendering said electrical means inoperative, and means operable after the commencement of a down-shift cycle for rendering said ignition circuit inoperative during movement of the gear shift element through its neutral position.

9. In a system including an internal combustion engine provided with an ignition circuit, a transmission mechanism connected to said engine and including a driving shaft and a driven shaft, means interposed between said shafts and operative to couple the former to the latter at various speed ratios including a relatively high speed ratio and a relatively low speed ratio, said means including a gear shift element movable in one direction from an extreme position through a neutral position to another extreme position to effect a transmission down-shift from said high speed ratio to said low speed ratio, a cyclicly operable electric motor controlling the displacement of said gear shift element, said electric motor being operable when the speed of the driven shaft falls below a predetermined speed to initiate a shift cycle and effect a transmission down-shift from said high speed ratio to said low speed ratio, and means operable after the commencement of a down-shift cycle for rendering said ignition circuit inoperative during movement of the gear shift element through its neutral position.

10. In combination, a transmission includin a driving shaft and a driven shaft, means interposed between said shafts and operative to couple the former at the latter at various speed ratios and including a gear shift element movable in one direction to effect a transmission up-shift and movable in the opposite direction to effect a transmission down-shift, cyclicly operable mechanism controlling the displacements of said gear shift element and including a reversible electric motor having a field winding, means operatively connecting said motor and element and operable when said motor is operated in one direction to move the element and effect a transmission up-shift and operable when said motor is operated in the other direction to move said element and effect a transmission down-shift, a pair of normally open electric circuits for said field winding and adapted when closed to pass electric current through said winding in opposite directions respectively to operate the motor in opposite directions, a normally open control circuit for each of said field winding circuits adapted when closed to effect closure of the respective circuit which it controls, a reversing switch movable between two positions, means operable when said reversing switch is in one position for pctentially closing one of said control circuits, means operable when said reversing switch is in the other position for potentially closing the other of said control circuits, means operable upon rotation of the motor in either direction upon completion of a transmission up-shift or down-shift for actuating said reversing switch to potentially close one of said control circuits to condition the motor for rotation in the opposite direction, and means operable when the speed of the driven shaft exceeds or falls below predetermined speeds of rotation for completing the potentially closed control circuit.

11. In combination, a transmission including a driving shaft and a driven shaft, means interposed between said shafts and operative to couple the former to the latter at various speed ratios and including a gear shaft element movable in one direction to effect a transmission upshift and movable in the opposite direction to effect a transmission down-shift, cyclicly operable mechanism controlling the displacements of said gear shaft element and including a reversible electric motor having a field winding, means operatively connecting said motor and element and operable when said motor is operated in one direction to move the element and effect a transmission up-shift and operable when said motor is operated in the other direcsion down-shift, a pair of normally open electric circuits for said field winding and adapted when closed to pass electric current through said winding in opposite directions respectively to operate the motor in opposite directions, electromagnetic relay means operable when energized to close one of said normally open circuits, electromagnetic relay means operable when energized to close the other of said normally open circuits, a reversing switch movable between two positions and operable when in one position to select one of said electromagnetic relay means for subsequent energization and operable when in the other position to select the other electromagnetic relay means for subsequent energization, means operable upon rotation of the motor in either direction upon completion of a transmission up-shift or down-shift for actuating said reversing switch to select one of said electromagnetic relay means and condition the motor for rotation in the opposite direction, and means operable when the speed of the driven shaft exceeds or falls below predetermined speeds of rotation for causing energization of a selected electromagnetic relay means.

12. In combination, a transmission including a driving shaft and a driven shaft, means interposed between said shafts and operative to couple the former to the latter at various speed ratios and including a gear shaft element movable in one direction to effect a transmission up-shift and movable in the opposite direction to effect a transmission down-shift, cyclicly operable mechanism controlling the displacements of said gear shift element and including a reversible electric motor having a field winding, means operatively connecting said motor and element and operable when said motor is operated in one direction to move the element and effect a transmission up-shift and operable when said motor is operated in the other direction to move said element and effect a transmission down-shift, a pair of normally open electric circuits for said field winding and adapted when closed to pass electric current through said winding in opposite directions respectively to operate the motor in opposite directions, electromagnetic relay means operable when energized to close one of said normally open circuits, electromagnetic relay means operable when energized to close the other of said normally open circuits, a reversing switch movable between two positions and operable when in one position to select one of said electromagnetic relay means for subsequent energization and operable when in the other position to select the other electromagnetic relay means for subsequent energization, cam means operable upon rotation of the motor in either direction upon completion of a transmission upshift or down-shift for actuating said reversing switch to select one of said electromagnetic relay means and condition the motor for rotation in the opposite direction, and means operable when the speed of the driven shaft exceeds or falls below predetermined speeds of rotation for causing energization of a selected electromag- 

